1. Field of the Invention
The invention relates to a device for recording an information signal on a magnetic record carrier, which device comprises
an input terminal for receiving the information signal, PA1 a write amplifier, having an input coupled to the input terminal and having an output coupled to an input of a magnetic head, which write amplifier is adapted to drive the magnetic head with a write current of a given amplitude, and PA1 compensation means for controlling the amplitude of the write current in dependence upon temperature variations which occur during recording.
2. Description of the Related Art
Such a device is known from Japanese Kokai 60-143,404.
The compensation means in the prior-art device comprise a temperature detector arranged close to the magnetic head. The temperature detector detects the temperature in the proximity of the magnetic head and generates a control signal whose magnitude is a measure of this temperature. Subsequently, the compensation means control the amplitude of the write current in dependence upon the control signal so as to obtain a constant magnetization level in the record carrier at varying temperature.
The recording depth of the information signal in the record carrier appears to be dependent on the temperature of the record carrier during recording. A varying temperature consequently results in varying recording depths.
The recording level of a recording should preferably be as constant as possible and should have a specific value. This is of particular importance in apparatuses which do not have an erase head and which realize a new recording by overwriting the old recording. In the case of a non-constant recording level of the old recording in the record carrier, problems may arise in the sense that sometimes the old recording cannot be overwritten satisfactorily. This poses a problem particularly in view of the compatibility of record carriers, which requires that it should be possible for a record carrier on which an old recording has been made to be overwritten by means of another recording device not comprising an erase head. This means that said requirement of a recording depth which is as constant as possible applies both to devices with an erase head and devices without an erase head.
If this requirement is not met, it will not be possible to realize a satisfactory readout when a new recording written over an old recording in devices without an erase head is to be reproduced. By correcting the amplitude of the write current for said temperature variations during recording, the desired recording depth can be achieved for the entire recording with a satisfactory overwrite attenuation, thus enabling a satisfactory read quality of the newly recorded information to be achieved. Nevertheless, it has been found that in some cases the recording depth during a recording is not sufficiently constant.